This is one of the things that I miss from earlier expansions (primarily TBC). While I do agree that it could've been improved and handled a bit better, I actually liked the concept of managing your threat as a DPS class. It was fun, and made it a bit more interesting to play when you didn't just stand around and do your rotation. It also made it easy to tell a good tank from an OK one.
Did Blizzard remove this element of gameplay due to player feedback, or did they just grow tired of it themselves? I'd love to see this type of threat management return. Perhaps not in LFR (that would be disastrous), but in Mythic perhaps. What do you think?